Updated release notes

com.unity.render-pipelines.lightweight/CHANGELOG.md

 - Updated the UI for the Lighweight pipeline asset.
 
 ### Fixed
+- PostProcessing wasn't working on VR
 - PS4 compiler error
 - Fixed VR multiview rendering by forcing MSAA to be off. There's a current issue in engine that breaks MSAA and Texture2DArray.
 - Fixed UnityPerDraw CB layout